>>We are talking about enforcement here. Putting bankers in jail instead of imposing a large fine on the corporation saves the banks money.
Maybe you live in a different reality, but in ours, the massive reputation hit the bank would suffer from having its employees go to jail would be tremendously more costly than meager fines that they can just shrug off.
Sure, but it's a zero sum game. The change in reputation of one bank won't affect the overall demand for banking services. From the point of view of the regulator trying to snag a private sector job, it doesn't matter. The same amount of banking business will continue to be done--if Bank A takes a hit Bank B will have more work and more jobs.
Consider that the OP is about Abacus, a financial product created by Goldman Sachs at the request of a speculator. If more exotic products like that are tainted by evidence of systemic corruption and the possibility of having to spend time in court, then customers may well choose to park their money in boring stock or bond index funds, which give the banks a much smaller cut. So it's not a zero sum game.
Maybe you live in a different reality, but in ours, the massive reputation hit the bank would suffer from having its employees go to jail would be tremendously more costly than meager fines that they can just shrug off.